bitbake: layerindex: Fix bitbake-layers layerindex-show-depends command

Running 'bitbake-layers layerindex-show-depends meta-filesystems' fails with:
```
Traceback (most recent call last):
  File "<...>/poky/bitbake/bin/bitbake-layers", line 93, in <module>
    ret = main()
  File "<...>/poky/bitbake/bin/bitbake-layers", line 86, in main
    return args.func(args)
  File "<...>/poky/bitbake/lib/bblayers/layerindex.py", line 209, in do_layerindex_show_depends
    self.do_layerindex_fetch(args)
  File "<...>/poky/bitbake/lib/bblayers/layerindex.py", line 182, in do_layerindex_fetch
    args.shallow)
AttributeError: 'Namespace' object has no attribute 'shallow'
```

Initialize the shallow attribute to fix it.

(Bitbake rev: 71f095c147fe6aa7b5e6272002e0498cf9494256)

Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/bitbake/lib/bblayers/layerindex.py b/bitbake/lib/bblayers/layerindex.py
index b2f27b21ee..17dfc9874d 100644
--- a/bitbake/lib/bblayers/layerindex.py
+++ b/bitbake/lib/bblayers/layerindex.py
@@ -206,6 +206,7 @@ class LayerIndexPlugin(ActionPlugin):
 """
         args.show_only = True
         args.ignore = []
+        args.shallow = True
         self.do_layerindex_fetch(args)
 
     def register_commands(self, sp):